The decision by three judges from the U.S. 9th Circuit Court of Appeals upsets gay couples in California who had hoped to wed this week. But a legal expert says the ruling could be a strategic victory for Prop. 8 opponents.

A federal appeals court decided Monday to put same-sex marriage in California on hold at least until December, interrupting the wedding plans of scores of gay couples who were hoping to exchange vows later this week.

The brief order by a three-judge panel of the U.S. 9th Circuit Court of Appeals prevents an early showdown on the marriage question at the U.S. Supreme Court. Challengers of the marriage ban said they would not appeal Monday's order.

U.S. District Judge Vaughn R. Walker decided Aug. 4 that Proposition 8 violated the U.S. Constitution and later ordered gay marriage to resume at 5 p.m. Wednesday unless a higher court intervened. The panel's decision gave no explanation for staying Walker's order directing the state to once again allow same-sex couples to marry.

The panel said the court would hear the Proposition 8 challenge on an expedited basis and hold arguments the week of Dec. 6. Another panel of three judges is expected to rule on the appeal.

Loyola Law School professor Richard Hasen said Monday's order was strategically advantageous for supporters of same-sex marriage, no matter how disappointed many couples may be. If the panel had refused to place a hold on Walker's ruling, the supporters of Proposition 8 were prepared to seek a stay from the Supreme Court. The court is believed to be divided on the question of gay marriage, with Justice Anthony Kennedy considered a swing vote. A vote on a hold might have pushed the justices into taking an early position on the question.

"I think there are strategic reasons why even the most ardent supporter of gay marriage could opt for a stay," said Hasen, an expert on federal court stays. "The concern is that rushing things to the Supreme Court could lead to an adverse result [for supporters of gay marriage.] If this case takes another year to get to the U.S. Supreme Court, there could be more states that adopt same-sex marriage and more judicial opinions that reach that conclusion."

Hasen said the hold "takes the heat" off Kennedy and takes the case "off the front burner for a while."

The proponents of Proposition 8 won an early round at the Supreme Court in January, just as Walker was to begin hearing trial testimony about Proposition 8. The court ruled 5 to 4, with Kennedy in the majority, to overturn a decision by Walker to permit portions of the testimony to be broadcast.

"California voters spoke clearly on Prop. 8, and we're glad to see their votes will remain valid while the legal challenges work their way up through the courts," said Andy Pugno, general counsel for ProtectMarriage.

"Invalidating the people's vote based on just one judge's opinion would not have been appropriate and would have shaken the people's confidence in our elections and the right to vote itself."

The 9th Circuit panel, which legal analysts said included a conservative, a moderate and a liberal, also indicated that the court has serious questions about whether the Proposition 8 sponsors have legal authority to appeal Walker's conclusions about the constitutionality of the ban.

The court ordered ProtectMarriage to address why it believes it has legal authority to appeal in its opening brief. Normally, only those directly affected by a judge's order can appeal.

Gov. Arnold Schwarzenegger and Atty. Gen. Jerry Brown, the defendants in the case, have refused to do so and instead called for same-sex marriages to resume as soon as possible.

Attorneys for two same-sex couples who are challenging Proposition 8 had asked the 9th Circuit to permit marriages to proceed.

The challengers of the measure said Monday they were grateful that the court agreed to expedite its review of Walker's decision.

"While today's 9th Circuit Court ruling is a disappointment for many of us who agree with Judge Walker's decision that marriage discrimination is unconstitutional, I am heartened by the court's decision to resolve the appeal on an expedited schedule," said San Francisco Mayor Gavin Newsom.

Theodore Boutrous Jr., one of the attorneys for the challengers, said the legal team was "very cognizant of the desire of so many people to get married" and had "strongly opposed" the legal hold.

"But we think at this point the best thing is for us to focus on the merits of the case in the 9th Circuit and of getting a victory as quickly as possible," Boutrous said. "We are ready to go."

ProtectMarriage had argued that gays who married before higher courts decided an appeal would have their marriages placed under a cloud of uncertainty.

Legal experts said it was not clear whether such marriages would survive if the Supreme Court eventually upholds Proposition 8.

UC Irvine Law School Dean Erwin Chemerinsky said it was "understandable" that the court "would want to preserve the status quo" pending a final ruling.

But he said he believed Monday's order could not "be reconciled with well-established law in terms of what is required for a stay." To block the effect of a ruling, an appealing party must show that it is likely to prevail on appeal and that it will suffer irreparable harm unless the ruling is blocked.

The Alliance Defense Fund, a Christian liberty group that is helping finance the defense of Proposition 8, called the 9th Circuit's decision "clearly the right call."

"Refusing to stay the decision would only have created more legal confusion surrounding any same-sex unions entered while the appeal is pending," said Jim Campbell, the fund's litigation counsel.

"This case has just begun. ADF and the rest of the legal team are confident that the right of Americans to protect marriage in their state constitutions will ultimately be upheld."